In recent years, the miniaturization of electronic components has been demanded along with the progress of communication technologies utilizing electromagnetic waves in the microwave region, such as automobile telephones, cell phones and satellite broadcasting. In order to achieve the demand, individual components constituting electronic components need to be miniaturized.
Dielectric ceramic compositions are used, in these electronic components, as materials for dielectric resonators, filters, laminated inductors, laminated capacitors and high-frequency components obtained by compositing them. For example, the size of a dielectric resonator is inversely proportional to the square root of a dielectric constant of a dielectric material in the case of utilizing the same resonance mode. Therefore, in order to fabricate a small dielectric resonator, a dielectric material having a high dielectric constant is needed. With respect to properties of a dielectric material for the microwaves, it is required that the dielectric loss tan δ (=1/Q) in the microwave region is low, that is, the Q value is high, the temperature coefficient τf of the resonance frequency is as near to zero as possible, and so on.
It is further necessary that internal electrodes for dielectric resonators, filters, laminated inductors, laminated capacitors and the like used in the microwave region, and the like be composed of conductors having a low resistance loss in the microwave band, such as silver, copper and gold. In order to miniaturize these electronic components for the microwaves, laminated electronic components are used which are obtained by simultaneous firing of laminated structures of dielectric ceramic compositions and internal electrodes. In this case, in order to fire a conductor having a low melting point, such as silver (melting point: 961° C.), copper (melting point: 1,083° C.) or gold (melting point: 1,063° C.), simultaneously with a dielectric material, the dielectric material needs to be one to be sintered at a temperature of 1,000° C. or lower, and preferably 900° C. or lower.
Patent Document 1 describes a material capable of being fired simultaneously with a dielectric ceramic composition and an internal electrode material such as silver, copper or gold, in order to miniaturize electronic components for the microwaves.
A capacitor built-in substrate has been proposed recently in which a ceramic layer having different properties is interposed as a multilayer inside a laminated electronic component. The ceramic having different properties includes high dielectric constant materials and magnetic materials. For example, in order to miniaturize a capacitance element, a built-in capacitor obtained by combining high dielectric constant materials is effective. Patent Document 1 discloses a multilayer wiring board bringing out an electrostatic capacity by using a built-in high dielectric constant ceramic insulating layer.    Patent Document 1: JP 2002-167274 A